The campaign aims to highlight the plight of child marriage in Asia, where one in nine girls are married before they turn 15.
Some passersby turned their heads in horror and muttered words of disgust from afar but not one person approached the newlyweds to question the situation.
Speaking to the Herald about the experience, Thompson said she found herself several times on the brink of tears.
Actors Kylie Thompson, 18, and Alan Fish, 55, played the parts of unhappy child bride and groom for the Herald-World Vision Not for Sale campaign. Photo / Supplied
"It makes you realise, wow, this actually is happening, and you kind of think about it a bit more," she said.
Thompson said she was a little disappointed more people didn't stop - because of how serious an issue it was.
"They probably weren't as outspoken as I thought they would be.
"There were actually quite a few people saying 'congratulations' and that kind of thing - which I found quite sad considering it's a young bride getting married off clearly when she doesn't want to be."
While hundreds of people witnessed the spectacle, at least half walked past without a second glance.
When approached later by the Herald, some of the people who had expressed concern gave a sigh of relief when they were told the pair were actors performing a stunt.
World Vision's National Director Grant Bayldon was happy with the response from some passersby but had an issue with the reactions.
Kylie Thompson acts part-time, alongside show-jumping and working with horses. Photo / Supplied
People's reactions simply weren't strong enough, he said.
"We got everything there from people not noticing to people noticing and being shocked, to people noticing and just shrugging it off."
"I guess that's the situation in the world at the moment - it's a huge issue for girls, child marriage, and it's something we need to create awareness of."
He said it was often difficult for someone walking past to know what they could do.
"I think it's an issue that people haven't really thought about here before.
"What we were doing was confronting people with something that is a major issue internationally, but they may have not been aware of before. "
On World Vision's decision not to enlist a minor to act out the role of child bride, Bayldon said the group wanted to highlight the problem, but wanted to avoid putting a child in the position of acting out the role.
"Just from the point of view of looking after the actor involved in the stunt," he explained.
"We were aware that photos of the actors would potentially be around online for a long time.
"So we wanted to make sure we were using an adult, so we weren't putting a child in the position that we might one day look back and wish they hadn't been a part of it."
Much like Thompson, the actor playing the role of the older groom felt society could have done better in reacting to the experiment played out before them.
Alan Fish said the experience suggested society was "so desensitised" we barely reacted to what was happening around us.
"That lack of reaction made you think, what does it take to get people motivated enough to actually create social change?"
Around 1.2 million children were trafficked each year worldwide, and more than half of all the children around the world aged between 2 and 17 experienced some form of violence.
